In the construction of both commercial buildings and homes, windows are an important architectural and functional feature. The primary use of windows in buildings of all types is to admit light and to permit occupants of the building to see the building surroundings through the window. An extremely important secondary purpose, is to use windows for the purpose of providing ventilation to the building interior. This is quite common in homes and apartment buildings. Many office buildings, however, currently are constructed with sealed windows which are incapable of being opened. In such office buildings, all ventilation necessarily is controlled by air handling equipment in conjunction with refrigeration and heating units.
In building construction where the windows are capable of being opened fully or partially, a variety of different techniques typically are employed. For residential use, "double-hung" windows are in relatively widespread use, particularly in colder climates. Double-hung windows are constructed with the upper half of the window either permanently in place or installed on a first pair of vertical tracks for vertical movement. The lower portion of the window is installed on a second pair of tracks, parallel to the tracks for the upper half, for vertical movement in a plane parallel to the plane of the upper half of the window. Consequently, the maximum window opening at any time is one-half of the total window frame area; and this opening is provided when either the top half is pulled all the way down or the bottom half is lifted all the way up to its maximum position. There are intermediate positions of both the top and bottom portions of the window which may be used to provide varying amounts of ventilation.
Another type of window which is capable of opening a greater portion of the window frame area for ventilation is a casement window. Such windows typically are hinged at the top and bottom at one side of the frame, and a crank mechanism is used to swing the window toward and away from the window frame opening. When the window is pivoted to a position in a plane substantially 90.degree. to the plane of the frame opening, the entire frame area is open to permit ventilation. Again, varying degrees of opening are provided by pivoting the window outwardly at different angles from the fully closed position to the fully opened position. When the window is open to its more extended positions, however, considerable stress is produced on the operating hardware in the event winds of any substantial amount blow against the extended window.
In some parts of the country, horizontal sliding windows, which move in tracks across the window opening (as contrasted to double-hung windows which move vertically) are used. The structure for such sliding windows is relatively simple, and these windows are among the most inexpensive to build and install. Sliding windows are extensively used in moderate climates; and when such windows are in their "fully open" position, one-half of the window opening encompassed by the window frame is open for ventilation.
In all of the window constructions mentioned above, ventilation may be provided; but when such windows are used in a large building, such as an apartment building, the aesthetic appearance of the building is significantly affected by the different window positions of the windows in different apartments or rooms of the building. For example, some windows will be fully closed, with the window lines provided by the frames and the window sashes producing the aesthetic effect envisioned by the architect in the original building design. Whenever any of the windows of the types mentioned above, however, are open or partially open in any of the other rooms of the building, the architectural lines are broken or interrupted in varying amounts depending upon the position of the window sash.
In addition to significantly altering the aesthetic appearance of the building, whenever any of the windows of the above type are open to any great extent, the security of the building is significantly impaired since the window opening provides ready access for entry. Consequently, when security is a concern, the windows must be closed and locked or opened only a slight amount and locked in place to prevent unauthorized entry into the building through the window opening. Partially opened windows provide significantly less ventilation than a widely opened window, as is readily apparent.
In an effort to overcome the disadvantages of the standard window sash opening constructions discussed above, some attempts have been made to provide a "stand-out" type of window opening. Stand-out window opening is achieved by moving the entire window and window sash outwardly from the window frame in a plane parallel to the opening in the window frame. One patent disclosing such a construction is the Perreton U.S. Pat. No. 2,374,618. The window structure disclosed in this patent has the sash mounted on opposite vertical edges to a scissors lever structure, the other portion of which is mounted in the frame. The window then is moved outwardly by means of a handle attached to one of the legs of the scissors mechanism to cause it to move from a fully closed position to a "stand-out" position located a few inches away from the frame opening. The scissors mechanism, however, is relatively bulky and cumbersome.
Two other patents which disclose systems for providing limited movement of the entire window sash outwardly in a plane parallel to the plane of the window frame, are the Barber U.S. Pat. No. 497,296 and Abbott U.S. Pat. No. 531,244. The Barber Patent uses another variety of a scissors type lever arm mechanism which requires a relatively thick wall or window frame to accomodate the mechanism. The mechanism itself also employs long intersecting lever arms mounted at the side of the window frame for effecting the motion of the sash relative to the frame. Because of the nature of the construction, the frame thickness or wall thickness for holding the operating mechanism must be equal to the maximum outward movement of the window sash.
The Abbott Patent discloses a window mechanism using a crank and rack gear for operating an eccentric mechanism for controlling the outward movement of the window. For a mechanism having parts of reasonably small size, only very limited outward movement of the window sash is possible with the structure of this device.
An advantage to "stand-out" window opening mechanisms, however, is that when the window is partially or fully opened, the architectural features of the building in which the window is placed, are not altered. All of the horizontal and vertical lines of the window sash and window opening are in the same orientation as when the window is fully closed. This is to be contrasted with sliding windows and double-hung windows where the window must be fully open or fully closed in order not to change the lines of the building. This is a significant advantage over casement windows which pivot outwardly to drastically change the appearance of any building in which they are used.
In addition to the architectural aesthetic advantage noted above for "stand-out" windows, such windows also are capable of providing significant ventilation with a relatively small amount of movement, due to the fact that the windows are open on all four sides to admit air into the building or exhaust air from the building. Consequently, a window which moves outwardly only a small number of inches is capable of providing the same ventilation as a double-hung window in its fully open position.
It is desirable to provide a window opening mechanism which provides the advantages of a "stand-out" window opening, but which is not subject to the disadvantages of the cumbersome operating mechanisms of the prior art.